So then no medium — NOS4A2

The phenomenal character of experience is the medium, e.g. colours, which can differ between individuals despite looking at the same object and interacting with the same wavelengths of light.

If there is no visor or screen, through which medium are you viewing an apple indirectly? — NOS4A2

The phenomenal character of experience; the thing that occurs when we dream, when we hallucinate, and also when we're awake and looking at real objects in the world.

It was part of a larger argument. Their direction and the fact that they interact with the environment allow anyone to explain how we can see an apple, for example, while it precludes you from doing the same. You have no way to explain how you can see a perception, or some other mind-stuff, and are resigned to illustrating diagrams of apples in thought-bubbles floating around a head. — NOS4A2

On indirect perception of apples:

A society of people who wear visors with sensors on the outside and a screen on the inside that displays a computer-generated image of the outside can see apples, albeit indirectly. There's nothing problematic about this. The indirect realist simply argues that this sort of indirect perception of apples happens even without the visor and its screen.

On direct perception of mental phenomena:

Despite your previous objections to the language, it is perfectly ordinary and correct to say that schizophrenics see and hear things when they hallucinate. The things they see and hear are mental phenomena, not nothing — else there would be no distinction between hallucinating something and not hallucinating anything, or between a visual hallucination and an auditory hallucination, or between a visual hallucination of one thing and a visual hallucination of another thing. This sense of seeing and hearing things also occurs during "veridical" perception, and it is only in virtue of this that we see and hear objects in the world — e.g. if there's damage in the visual and auditory cortexes but otherwise functional eyes and ears then we don't see or hear anything.

Your response attempts to push the discussion back into the traditional framing, whereas my view rejects that framing. — Esse Quam Videri

I think the issue I have is that you're arguing that the traditional dispute is framed wrong whereas I think that the traditional dispute just means something else by "direct perception". So perception might not be direct in the way that they mean even if it's direct in the way that you mean. Once again, I'll refer to semantic direct realism.

Regardless, thanks for the discussion.

There isn't a shared assumption of "phenomenal mirroring". There is the direct realist's claim that there is "phenomenal mirroring", because that is what it would mean for ordinary objects to be "directly present" in experience, and the indirect realist's claim that there might not be "phenomenal mirroring", because ordinary objects are not "directly present" in experience.

As for the "epistemic intermediary" I still fail to understand what you mean by the term. All indirect realists would mean by it is that we believe that the ball is blue and round because the ball appears blue and round, and that this appearance is a mental phenomenon, not the "direct presentation" of the ball's colour and shape.

I disagree with your assertion that we must be able to determine which group someone belongs to for there to be two different groups.

A scenario like the below, where two humanoid aliens agree that the strawberry reflects 400nm light and that the proposition "the blugleberry is foo-coloured" in their language is true, is intelligible:

Senses have a direction that tends toward the outside of the body. — NOS4A2

What does it mean to say that senses have a "direction"?

It’s why we have those holes in our skull where our eyes, nose and mouth are, so they can better interact with the environment. It’s why you turn your head towards something or open your eyes in order to see it better. — NOS4A2

If you just mean to say that (most of) our sense receptors are situated on the outside of our body and react to things that exist outside the body then, to be blunt, no shit.

If you think that this is all it means for perception to be direct then you're very mistaken. Indirect realists don't disagree with any of the above.

Like your prior suggestion that we directly perceive an object if (and only if?) our sense organs are in direct physical contact with the object perceived, you're presenting a very impoverished interpretation of the issue.

The visor-and-screen case counts as indirect precisely because it introduces such a surrogate: the subject’s epistemic access runs through an internally generated stand-in whose adequacy must be assessed. That is not true in ordinary perception, even though both cases involve world-directed judgments. — Esse Quam Videri

Then we're back to what I asked in this post (which I'll repeat below), which I don't think was addressed:

What's the difference between a bionic eye that is "integrated into perception such that judgments are still answerable to objects through ongoing interaction and correction" and a bionic eye that is "a surrogate whose adequacy depends on a generating process that stands in for the world"?

It just seems like there's a lot of special pleading here.

Whether an organic eye or a bionic eye, there is something that takes electromagnetic radiation as input, carries out transduction according to some deterministic process, and then stimulates the optic nerve.

Without begging the question or engaging in circularity, what determines whether or not the physical intermediary between the electromagnetic radiation and the optic nerve is an epistemic intermediary?

I don’t think there’s a non sequitur here once my notion of “directness” is kept in view. — Esse Quam Videri

As I said before, you can mean anything you like by "directness". I'm concerned with what it means in the context of the traditional dispute between direct and indirect realism, which I summarised here (which I'll repeat below), and which I also don't think was addressed:

The direct realist argues that the sky appears blue because a) the sky is blue and b) the sky is directly present in experience. The indirect realist argues that this argument fails because (b) is false.

Even if there's an interpretation of (a) such that (a) is true, indirect realists aren't arguing that (a) is false; they are arguing that (b) is false. And they aren't arguing that any and all interpretations of (b) are false but that a particular interpretation of (b) is false; specifically, the interpretation of (b) such that if it were true, and if the sky appears blue, then (a) is true according to a naive interpretation of (a).

I would say that orientation is frame-relative in a way that shape is not. — Esse Quam Videri

Shape as seen or shape as felt? Because these are very different things. Studies on Molyneux's problem show that those born blind who have their sight restored "had no innate ability to transfer their tactile shape knowledge to the visual domain".

So is the mind-independent "shape" of an object similar to the look of a shape or the feel of a shape? Or is it similar to neither, and like colour we using a word like "circle" to refer to distinct things that are causally related but fundamentally different?

Or for something that might be less tricky to understand; what looks to be a smooth circle with the naked eye may look very different through a pair of binoculars or a microscope. Which "zoom" or "scale" counts as the "real" shape of an object? Same question when discussing something as simple as the distance between two points (2cm looks very different through a magnifying glass).

Colour is plausibly response-dependent in a way that shape and orientation are not. Ordinary claims about shape and orientation track relatively stable, mind-independent structural features of objects — and that’s why geometrical error correction, measurement, and intersubjective agreement work the way they do. — Esse Quam Videri

Then to incite a more controversial topic:

Consider that there are two subspecies of humanity such that what one sees when standing upright is what the other sees when standing upside down. Both groups use the word "up" to describe the direction of the sky and "down" to describe the direction of the floor. Firstly, is this logically plausible? Secondly, is this physically plausible? Thirdly, does it make sense to argue that one subspecies is seeing the "correct" orientation and the other the "incorrect" orientation? Fourthly, if there is a "correct" orientation then how would we determine this without begging the question?

If it's difficult to imagine, consider two astronauts top and tail in space or standing on opposite sides of a ringworld looking at the Earth. From the perspective of one the North Pole is as the top and from the perspective of the other the South Pole is at the top. Neither is the "correct" perspective as there are no privileged viewpoints. Now retain their orientation relative to one another but bring them to Earth. Is there some distance from the ground such that one of their perspectives becomes the "correct" orientation?

Calling my view “Cartesian” doesn’t address the issue I’ve been pressing. The Cartesian Theatre is defined by the presence of an epistemic surrogate whose adequacy must be evaluated. My whole point has been that once phenomenal experience is not truth-apt, treating it as the “immediate object of perception” does no epistemic work. If that move reclassifies the traditional taxonomy, so be it—but that’s a consequence of rejecting phenomenal-first assumptions, not a reductio. — Esse Quam Videri

I'm not calling your view Cartesian. I'm saying that the scenario with the visor and the screen functions like a Cartesian Theatre. This would clearly be indirect perception even though their perceptual judgement "there is a ship" is about an object in the world.

So your claim that "perception is cashed out entirely in terms of perceptual judgment, and perceptual judgments are about objects in the world ... [therefore perception is direct]" is a non sequitur.

I've granted that "blueness" is not a property of the sky, yet I maintain that "the sky is blue" is true. This sounds like a contradiction, but I don't think it is.

I would say that ordinary perceptual judgments like "the sky is blue" do not have to be interpreted in a naive way, but can be interpreted as something like "under normal viewing conditions, the sky systematically elicits blue-type visual responses in normal perceivers". This makes the claim objective, fallible, publicly assessable and non-projective. Nor does it require that the sky instantiate a phenomenal property as experienced. Many of the claims that people make ("the sun is rising", "that table is solid") can be cashed out in similar terms without resorting to naive realism. — Esse Quam Videri

So there's an interpretation of (a) such that (a) is true. However, notice that indirect realists aren't arguing that (a) is false; they are arguing that (b) is false. And they aren't arguing that any and all interpretations of (b) are false but that a particular interpretation of (b) is false; specifically, the interpretation of (b) such that if it were true, and if the sky appears blue, then (a) is true according to a naive interpretation of (a).

But out of curiosity, would you make the same claims about shape and orientation (and other features of geometry) that you make above about colour?

It's not conflation, it's deflation. In the view I am defending, perception is cashed out entirely in terms of perceptual judgment, and perceptual judgments are about objects in the world. That’s not to deny that sensation causally mediates perception, only that it epistemically mediates it. — Esse Quam Videri

Then I'll repeat what I said to Banno in my last comment to him: I think the visor and its screen functions exactly like a Cartesian theatre (which is a strawman misrepresentation of indirect realism), and a Cartesian theatre is exactly the sort of thing that would qualify as indirect perception. So you've defined "direct realism" in such a way that even the strawman misrepresentation of indirect realism would count as direct realism.

It's so divorced from the actual (traditional) dispute between direct and indirect realism that it's not deflation but ... avoidance?

If you agree that phenomenal experience cannot be correct or incorrect, then the hypothesis that phenomenal experience is "what is directly seen" no longer explains error or motivates the skeptical worries you have presented. — Esse Quam Videri

The skeptical worry is that the sky appears blue but might be green (or not coloured at all, because colour is a "secondary quality") and that the ball appears round but might be cubed (or not shaped at all, because shape is a "secondary quality"). The direct realist tries to avoid this by arguing that the sky appears blue because a) the sky is blue and b) the sky is directly present in experience. The indirect realist argues that this argument fails because (b) is false.

You appear to be arguing that (a) is a category error (i.e. colour is not even the sort of property the sky can have). That neither proves direct realism nor disproves indirect realism. If anything, it proves indirect realism because if (a) is a category error then (b) is false.

My point has been that the direct object of perceptual judgments ("That's a ship") are objects in the world. Another way to say this is that perceptual judgments about objects in the world (ships), not phenomenal contents (redness as-seen, sourness as-tasted, etc). And this pretty much brings us full circle to where we landed a few posts back. — Esse Quam Videri

And so we circle back to the example with the visors. The judgement "there is a ship" is a judgement about an object in the world, but it still involves indirect perception of the ship given the visor and the screen. You seem to be conflating the immediate objects of perception and the things our judgements are about. These are not the same thing.

What do you mean by senses "pointing" outward? The physics and physiology is just nerve endings reacting to some proximal stimulus (e.g. electromagnetic radiation, vibrations in the air, molecules entering the nose, etc.) and then sending signals to the brain. If there's any kind of "motion" involved, it certainly does appear to be towards the head.

We start with the naive view that there is (usually) a match between the phenomenal character of experience and the world. The sky is blue in the exact same way as blueness is present in visual experience and the ball is round in the exact same way as roundness is present in visual experience. We can trust that this is so because the sky and the ball are "directly present" in experience; experience isn't just some distinct neurological or mental phenomenon but an "openness to the world". And this is understandable, particularly with distance being a feature of visual experience. It really seems as if experience extends beyond the body to encapsulate the environment.

The indirect realist then argues that experience is just a neurological or mental phenomenon and so the sky and the ball are not "directly present" in experience in this way. Because of this, it is possible that the sky appears blue to us but is in fact green (or not coloured at all, because colours are "secondary qualities") and that the ball appears round to us but is in fact a cube (or not shaped at all, because shapes are "secondary qualities"). When I see the sky the "immediate object of assessment" is the colour blue, which is a mental phenomenon, and when I see the ball the "immediate object of assessment" is the round shape, which is a mental phenomenon.

I think that the distinction you're making here is more terminological than substantive — Esse Quam Videri

I would say the same about your claim that experience isn't the sort of thing that can "succeed" or "fail" at "lin[ing] up with how things are".

Just because an apple isn't a "representation" it doesn't follow that we can't say that its features/properties do or don't match the features/properties of some other apple (or some other fruit).

In the case of naive realism, the claim is that the features/properties of experience do match the features/properties of the apple (in the veridical case), in the sense of both type identity and token identity. The indirect realist argues that this token identity fails and so this type identity possibly fails.

And if we find that colours and shapes aren't even the sort of properties that the sky and the ball can have (which I think we have, at least with respect to colour) then that's just proof of indirect realism as I see it.

You’re treating phenomenal character as that which is assessed for correctness in the act of perception — Esse Quam Videri

No, I'm saying that it's the thing directly seen. From this we then make judgements about the world that can be correct or not (if indeed we do; much of the time I experience things without making any kind of judgement).

In veridical perception, that judgment is answerable to objects in the environment and can be corrected by further interaction with them. In hallucination, the same kind of judgment is made, but it fails—there is no object that satisfies it. No inner surrogate is thereby promoted to the status of what is assessed; rather, the judgment is simply false. — Esse Quam Videri

As I said a few days ago, these judgements do not occur apropos of nothing. Excluding the obvious cases of mathematics and logic, it is the phenomenal character of experience that prompts and directs our judgements. I say "there is a white and gold dress" when the appropriate visual phenomena occurs. If the experience is veridical (to the extent that colour experiences can be veridical), the judgement is true. If the experience is an hallucination, the judgement is false. In either case it is the visual phenomena (including its character) that acts as "immediate object of assessment".

If the bionic eye is integrated into perception such that judgments are still answerable to objects through ongoing interaction and correction — as with natural, transplanted, or lab-grown eyes — then there is no epistemic intermediary, and perception is direct in the sense I’m using.

The visor and nerve-stimulation cases differ because they interpose a surrogate whose adequacy depends on a generating process that stands in for the world, rather than being part of the perceptual relation itself. — Esse Quam Videri

What's the difference between a bionic eye that is "integrated into perception such that judgments are still answerable to objects through ongoing interaction and correction" and a bionic eye that is a "surrogate whose adequacy depends on a generating process that stands in for the world"?

It just seems like there's a lot of special pleading here.

Whether an organic eye or a bionic eye, there is something that takes electromagnetic radiation as input, carries out transduction according to some deterministic process, and then stimulates the optic nerve.

Without begging the question, what determines whether or not the physical intermediary between the electromagnetic radiation and the optic nerve is an epistemic intermediary? I don't think there is such a thing, e.g. proteins are not privileged over silicon.

So either perception is direct both with the bionic eye and the organic eye or perception is indirect both with the bionic eye and the organic eye.

If you say that perception is direct both with the bionic eye and the organic eye then we return to the Common Kind Claim: whatever is the "immediate object of assessment" when the eye (whether bionic or organic) is "malfunctioning" must also be the "immediate object of assessment" when the eye isn't "malfunctioning" — and in the former case that thing cannot be an object in the external world because the thing we're seeing doesn't exist in the external world; therefore in the latter case that thing cannot be an object in the external world either.

I would say that there is no relevant difference of the kind you are asking for — because the distinction I’m drawing is not about the material or biological status of the causal chain at all — but about the epistemic role it plays.

In ordinary perception — regardless of whether the eye is natural, transplanted, or artificially grown — one’s judgments are answerable to objects in a shared environment through ongoing interaction and correction... — Esse Quam Videri

So why is this not also the case for the bionic eye? It simply replaces rod and cone cells with silicon chips.

In both cases, what the subject’s judgments are immediately answerable to is a generated input whose correctness depends on how it was produced, rather than to the objects themselves. That is the sense in which the perception is indirect. — Esse Quam Videri

Then what is the relevant difference between these:

1. An artificial bionic eye
2. An artificial organic eye (identical to a natural eye, but grown in a lab)
3. A transplanted natural eye
4. The natural eye one was born with

All work by taking electromagnetic radiation as input and then stimulating the optical nerve according to some deterministic process.

The visor case is instructive precisely because it introduces an epistemic intermediary whose outputs are the immediate objects of assessment. — Esse Quam Videri

So let's amend the scenario slightly. Instead of there being a screen on the inside that outputs light towards the eyes it has wires connected directly to the optical nerves and stimulates them in the "appropriate" way, i.e. the visor is a "bionic eye".

Would you still accept that these people only have indirect perception of the world beyond the visor, or does it now qualify as direct perception? What are the immediate objects of assessment? If the Common Kind Claim is to be believed then whatever are the immediate objects of assessment when the bionic eye is malfunctioning (e.g. causing their wearers to see things that aren't there) are also the immediate objects of assessment when it's working as intended.

For the direct realist, the chain is the mechanism by which the world shows itself... — Banno

The problem with this is that it makes the word "direct" in the phrase "direct perception" meaningless. This is highlighted by your assertion that these people with their visors still directly perceive their shared environment. You appear to be arguing that the visor and its screen is "the mechanism by which the world shows itself".

Whereas I think this visor and its screen functions exactly like a Cartesian theatre, and a Cartesian theatre is exactly the sort of thing that would qualify as indirect perception (but isn't required for indirect perception, as I've argued before). So you've defined "direct realism" in such a way that even the strawman misrepresentation of indirect realism would count as direct realism.

And while they are seeing the image on the screen and they are seeing the ship and they are talking about the ship, each of these has a slightly differing sense, each is involved in a different activity. — Banno

According to the indirect realist, the same is true ("each of these has a slightly differing sense") even without the visor.

1. There is perceiving mental phenomena (e.g. colours in the sui generis qualitative sense of the term) — which is not to be understood in the sense of a Cartesian theatre but in the sense of the seeing and hearing that (also) happens when we dream and hallucinate.

2. There is perceiving distal objects (e.g. a dress).

3. There is talking about the mental phenomena (e.g. "I see white and gold").

4. There is talking about the distal object (e.g. "there is a dress").

The substantive philosophical claims are that a) (2) only happens in virtue of (1) and that b) (2) does not satisfy the philosophical notion of directness, e.g. as explained here — with the example of the visor showing that (2) doesn't need to be direct for (4) to happen.

So here's the thing; anyone can mean anything by the words "direct" and "indirect". It is possible that direct and indirect realists each mean different things by the words such that perception is direct in the sense that direct realists mean by the word "direct" and that perception is not direct in the sense that indirect realists mean by the word "direct", and so that the dispute is nothing more than two groups of people talking past each other.

But I don't think that this is the case, at least traditionally. I think that both groups mean the same thing by the words. I think that naive colour primitivism is exactly what was meant by direct realism, with Locke's distinction between primary and secondary qualities being exactly what was meant by indirect realism. This appears consistent with the definition of direct realism as explained here, where one of the stipulations is that "the phenomenal character of experience is determined, at least partly, by the direct presentation of ordinary objects".

You used the phrase "perception relates us directly to mind-independent objects", but what exactly does it mean for perception to "relate us directly" to mind-independent objects? Consider this example of a society of people who wear visors with sensors on the outside and a screen on the inside displaying a computer-generated representation of their environment. Does their perception "relate them directly" to their environment? They certainly can talk about and make judgements about their environment, but must there be more to it? Will you say that these people "directly perceive" their environment, as Banno says? You're more than welcome to define "direct perception" in such a way that such a proposition is true, but I think it very obvious that this is not what is traditionally meant, either by indirect realists or their direct (naive) realist opponents, both of whom will agree that these people do not directly perceive their environment (even if they disagree over whether or not these people directly perceive the screen). Once again, I think it's semantic direct realists introducing a philosophy distinct from phenomenological direct realism, and which is consistent with (phenomenological) indirect realism (as that article argues).

I was referring to the example of the people with visors on their heads, with sensors on the outside and a screen on the inside displaying a computer-generated representation of their environment.

Even if direct realists want to argue that these people directly see the screen on the inside of the visor they must accept that they do not directly see the environment outside the visor. Yet these people can still talk about the environment outside the visor, not only about their screens.

So Banno's argument that if indirect realism is true then we can only talk about our private experiences is evidently invalid. We don't need direct perception of something to talk about it.

The mere possibility of global deception does not by itself show that perception is indirect, nor that the world is not as it appears. — Esse Quam Videri

This has it backwards. The indirect realist claim is that because a) perception is indirect b) the world might not be as it appears and so c) there are legitimate grounds for scepticism, and the direct realist claim is that because d) perception is direct e) the world is as it appears and so f) there are no legitimate grounds for scepticism.

I'm not using (c) to justify either (a) or (b). I am:

1. Citing sources that show that in the context of this discussion the meaning of the phrase "direct perception" is such that if (d) is true then (e) is true
2. Arguing that our scientific understanding of the world shows that (e) is false (e.g. naive colour primitivism is false)
3. Concluding that (d) is false and that (a) is true

I can understand you arguing that (c) does not follow from either (a) or (b) and that (f) does not follow from either (d) or (e), but I think this is secondary to the primary issues of (a), (b), (d), and (e).

One simply judges that there is a ship, and that judgment is assessed over time by its coherence with other judgments, its responsiveness to further experience, and its success or failure in inquiry. — Esse Quam Videri

All of which can happen if we are hallucinating ships. In the extreme sceptical scenario we are brains-in-a-vat. This is not to say that indirect realists argue that this is probable, only that this is possible. You could argue that such scenarios are fantastical and unfalsifiable, and so unworthy of consideration, but I don't see this as refuting the core claims that perception of the external world is indirect and that it is not as it appears.

By perceptual belief I mean something more ordinary and less theory-laden: they are beliefs about objects and states-of-affairs that are formed in ordinary perceptual contexts (e.g. “there is a ship”, “the screen is emitting orange light”, “the umbrella is wet”). — Esse Quam Videri

Okay, so this is where the Common Kind Claim comes in. If we accept that (2) is false (that perception is not direct) then the phenomenal character of an hallucination can be indistinguishable from the phenomenal character of a so-called "veridical" experience.

If my "background knowledge" is the same in both the "veridical" and the hallucinatory case (which surely it must be, unless hallucinations necessarily affect memory), and if the phenomenal character of an hallucination can be indistinguishable from the phenomenal character of a "veridical" experience, then how can I justify my belief that I am not hallucinating? Other than the (questionable?) assertion that I ought assume that all experience is "veridical" unless I have a good reason to believe otherwise, it would seem that I cannot justify such a belief.

Although I personally find these sceptical conclusions to be secondary to the primary issues of (1) and (2), and especially to (2). If the answer to (2) is "no" then indirect realism is correct, even if its further conclusions (and other assumptions) are unwarranted.

I think the issue is that your formulation of (1) already presupposes a particular conception of justification — namely, that perceptual beliefs are justified if and only if the world is “as it appears”. — Esse Quam Videri

Perhaps, but then by "perceptual belief" I mean "a belief that the world is as it appears". What do you mean by the term?

So to be very explicit, I'll rephrase (1):

1. Is direct perception required for us to be justified in believing that the world is as it appears?
2. Is perception direct?

If you want to argue that our perceptual beliefs (whatever they are) are justified even if the world isn't as it appears then I'm not sure it's relevant to the direct and indirect realist's concerns. This really depends on what counts as a perceptual belief.

Then we have two separate questions:

1. Is direct perception required for our perceptual beliefs about the world to be justified?
2. Is perception direct?

Direct and indirect realists likely agree that the answer to (1) is "yes", with direct realists arguing that the answer to (2) is "yes", and so concluding that our perceptual beliefs about the world are justified, and indirect realists arguing that the answer to (2) is "no", and so concluding that our perceptual beliefs about the world are not justified.

You appear to agree with the indirect realist that the answer to (2) is "no" but disagree with both the direct and indirect realist that the answer to (1) is "yes"?

I think you might be misinterpreting (1). It's not supposed to be interpreted as "does the phenomenal character of experience justify our beliefs about the world?" but as "are we justified in believing that the world is as it appears, i.e. that the phenomenal character of experience is (or resembles) the mind-independent nature the world?" (with naive colour primitivism being the exemplar of such a notion).

Then I really don't understand what you are trying to argue, or how it relates to the dispute between direct and indirect realism.

Again, the direct realists argued that a) the phenomenal character of experience is the direct presentation of mind-independent objects and their properties, such that b) we can infer (deductively, even) from the phenomenal character of experience that "there are in nature colors, of a distinctive kind that we are all familiar with, i.e., ... simple intrinsic, non-relational, non-reducible, qualitative properties".

Indirect realists argued that (a) is false, and so that because of this (b) is unjustified, and possibly false, i.e. it is possible that the mind-independent nature of the world is radically different to the phenomenal character of experience ("the world isn't as it appears").

phenomenal character is not truth-apt and cannot function as a premise — Esse Quam Videri

Phenomenal character isn't truth apt but the premise "I am experiencing such-and-such phenomenal character" is, and so this latter proposition can function as a premise. It's exactly how John and Jane come to their respective conclusions.

John
P1. Electromagnetic radiation with such-and-such wavelengths usually cause people to experience such-and-such phenomenal characters
P2. I am experiencing such-and-such (e.g. orange) phenomenal character
C1. Therefore, the screen is probably emitting electromagnetic radiation with such-and-such a wavelength (e.g. 600nm).

Jane
P1. Electromagnetic radiation with such-and-such a wavelengths usually cause people to experience such-and-such phenomenal characters
P2. I am experiencing such-and-such (e.g. red) phenomenal character
C1. Therefore, the screen is probably emitting electromagnetic radiation with such-and-such a wavelength (e.g. 700nm).

Without each P2 each C1 would be a non sequitur, and given that P1 is the same for both John and Jane there would be no explanation for why each C1 is different.

Consider the example of John and Jane that ↪Michael provided. Jane makes a perceptual judgment (“the screen is orange”) and infers that the wavelength of the light is between 590nm and 620nm. Appealing to an introspective judgment (“I am seeing orange”) in order to justify her perceptual judgment simply won’t convince anyone, including herself. If she really wants to justify her judgment that the screen is orange, she’ll need to appeal to her background knowledge (optics, screens, color-blindness, etc.) and further perceptual judgments about her environment (current lighting, viewing angle, screen filters, etc.). — Esse Quam Videri

I didn't mean to suggest that the phenomenal character of experience is sufficient to infer mind-independent facts about the environment (although the naive colour realist does suggest this, and is wrong). Obviously if neither John nor Jane know anything about electromagnetic radiation then they wouldn't infer anything about the wavelength of light emitted by the screen.

It doesn't follow from this that they don't infer mind-independent facts about their environment from the phenomenal character of experience. Given their background knowledge of electromagnetic radiation, computer screens, etc., it is then the phenomenal character of experience that allows them to choose between "the screen emits ~700nm light", "the screen emits ~600nm light", etc, with John's and Jane's different inferences being explained by them having different phenomenal experiences.

In your visor world, the visors drop out of the discussion when folk talk about ships. They are not seeing the image on the screen, they are seeing ship. — Banno

"Seeing" and "talking about" do not mean the same thing. They are seeing the image on the screen and they are seeing the ship and they are talking about the ship.

It simply doesn't matter what "drops out of [their] discussion". If it helps, consider us to be secret observers, e.g. the mad scientists who engineered these people. Their visors do not "drop out of" our discussion. We ought accept that they do not directly see their shared environment.

That's not a redefinition. — Banno

Yes it is. There is no reasonable account under which these people can be said to directly see the ship (as the term "directly" means in the context of the dispute between direct and indirect realism). A scenario like this is exactly what it means so see something indirectly.

All of this is presented as implicitly rejecting the idea that meanings are fixed by hidden reference-makers (phenomenal or physical), and treating meaning instead as constituted by the public criteria governing a word’s use within a practice. That is, there are in fact all sorts of internal things going on in your mind that may in fact be the cause of your utterances, but we don't fix meaning by those, but we fix it by usage. Your example makes that clear, showing that regardless of the internal causes, even when they are dissimilar across speakers, the language game makes sense upon relieance upon usage without worrying about the internal causes. — Hanover

And yet the example should show that the usage will change if the phenomenal character of experience changes, even though nothing about the strawberry or the light changes, so clearly the phenomenal character of experience also has something to do with the meaning of the word "foo" in their language.

Although, saying that the usage will change is somewhat ambiguous. It changes in the sense that they no longer describe strawberries as being "foo-coloured", but then that would also be true if rather than a secret surgery on their eyes someone secretly dyed strawberries (and every other "foo-coloured" thing). This will change which things are described as being "foo-coloured" but it doesn't follow that the meaning of the word "foo" has changed.

I think an important point to mention when we say "meaning is use" is that it completely disentangles metaphysics from grammar. Grammar answers the question of how we use words. When I say "I see a ship" and you ask what is a "ship," under a meaning is use analysis, the "ship" is defined by how it is used. If you start asking about the atomic structure of the ship and how the photons bounce off the boards to your optic nerve, you are answering a very different question. — Hanover

I agree that metaphysics and grammar are different things; I just disagree with the claim either that the phenomenal character of experience is not real or that it does not have anything to do with language. It's real, and like every other real (and even unreal) thing in the universe, we can talk about it.

the fact that they are "in a very real sense" referring to their beetle in their box doesn't mean we now get to understand what those beetles are. — Hanover

I'm not claiming that we do. I'm only showing that our words can, and do, refer to these beetles.

In a situation like the below, both may agree with the proposition "the strawberry is foo-coloured", and may even agree that the word "foo" (sometimes) refers to a disposition to reflect a particular wavelength of light, but I think it unproblematic to accept that the word "foo" also refers to the private phenomenal character of the individual's experience, even if neither can know the other's. If someone were to secretly surgically alter their eyes and/or brains such that the phenomenal character was switched then each would say "the strawberry is no longer foo-coloured" (and then be very confused when they measure the wavelength of light and detect no change).

For the sake of argument, let's assume that direct realism is true. I directly hear the sound waves being produced by my telephone. Do I (directly) experience the "causal link" between these sound waves and my mother on the other end of the line? No. Does this matter? No. Does it follow that I don't (indirectly) hear my mother talking? No. Is it possible that I'm being deceived and that it isn't really my mother speaking on the other end of the line? Sure. Am I justified in believing that it's probable? Not really.

The same principle applies to indirect realism; it just draws the line that separates the direct from the indirect at a different place in the world, and as I believe I showed with my example of the society of people with visors, this line can be drawn in such a way that nobody ever directly sees what another directly sees, and yet they can still have a functional language and knowledge of their shared environment.

As I clarified in my comment, I meant to say that I take no stock in the private language objection to indirect realism. You claimed that if indirect realism is true then we cannot talk about our shared environment, only our private experiences, and so that because we can (must?) talk about our shared environment then indirect realism is wrong. I showed that your premise is false, and so that your argument fails. These people do not directly see their shared environment (given the visors) and yet can still talk about it.

Indeed, it supports direct realism by showing that we routinely and intelligibly “see through” intermediaries without reifying them as perceptual objects. — Banno

You're seriously trying to redefine "direct perception" in such a way that even with these visors and their computer-generated images on a screen they still directly see their shared environment? This is absurd, and is precisely the problem I highlighted at the end of this post. You're taking what is very clearly indirect perception, butchering the meaning of the words "direct" and "indirect" to mean something else, and then taking this as proving the indirect realists of their world wrong. It's dishonest, and equivocation.

And their language would be public and therfore not disproving the PLA. The PLA is not dependent upon unmediated access to the environment. In fact, Wittgenstein says nothing about whether the world is mediated through the senses or not. He's talking about words and how they can have meaning. — Hanover

I slightly misworded my first sentence. I meant to say that I hold no stock in the argument that the PLA refutes indirect realism.

But on the PLA, let's assume that John's and Jane's screens each output different colours in response to the same wavelengths of light, but in a consistent manner. Do you accept that a) they will both use the word "foo" in their language when asked to describe the colour of grass, that b) there is a very real sense in which when they use the word "foo" they are referring to the colour output by their private screen, and that c) it is intelligible for each to wonder if the other's private screen outputs a different colour when looking at grass?

How is that in any way contrary to the private language argument? These folk are talking about their shared environment, not their unshared screen time... — Banno

I meant to say that I hold no stock in the argument that the PLA refutes indirect realism. You appear to be accepting that these people are talking about their shared environment even though none of them ever directly see it (which even the direct realist must accept given the visors). The only thing these people ever directly see (even assuming direct realism) is their private screen.

So your entire objection falls apart.

I hold no stock in the private language objection. A society of people born with unremovable visors on their heads with sensors on the outside and a screen on the inside displaying a computer-generated image of the environment could develop a language, talk about the environment, and lives their lives just as well as we can. Let's even throw in the inverted spectrum hypothesis and have different screens output different colours (but consistent for each individual), just for fun.

You are losing me here.

Sure, when we use a telephone we hear someone indirectly. Are you suggesting that undermines direct realism? — Banno

You said this, as if it were objectionable:

"Pretty ad hoc. Now we have both direct and indirect perception happening in the same individual for the same event."

It's not objectionable. It's quite ordinary. We just disagree on which things fall within the category "direct" and which things fall within the category "indirect".

Yep. But he is not only a mental image, or a firing of brain cells. He is public in a way that whatever indirect realists say they see, isn't.

It appears to me that you have moved on to equivocating about what it is that indirect realists suppose it is that is perceived. — Banno

You claimed that it's impossible to talk about things unless we can see them directly, and so I provided an example of something that we can talk about but haven't seen directly. So your objection fails.

We don't directly see Napoleon but can still talk about him. We don't directly see ships but can still talk about them.